1. Field of the Invention
This invention relates to a catalyst composition used for the conversion of hydrocarbon oils and more particularly to a method for hydrocracking of heavy hydrocarbon oils in the presence of a novel catalyst. Still more specifically, the invention concerns a catalyst composition having a novel pore structure for converting heavy hydrocarbon oils by reacting them with hydrogen in the presence of said catalyst. Still more specifically, the process provides a novel method for effective accomplishment of ring-scission reaction of the condensed ring compounds present in a heavy hydrocarbon oil, removal of sulfur and nitrogen compounds, and hydrocracking of such compounds.
2. Description of the Prior Art
Heretofore, for catalytically converting or refining hydrocarbon oils, it has been a common practice to use a catalyst obtained by carrying a metal component of Group VIII and/or Group VI of the Periodic Table (as described in "The Encyclopedia of Chemistry," Reinhold Publishing Corporation, second Edition (1966) at page 526) on a catalyst carrier such as silica and/or alumina, after or without subjecting such catalyst to a sulfiding treatment with a sulfur compound. It has been most common to use cobalt, nickel, molybdenum, tungsten or the like selected from metals of Group VIII or VI of the Periodic Table as a hydrogenating component. Such metals are used as oxides or sulfides described above.
However, as regards the catalyst carriers having acidity and activity for hydrocarbons, the catalytic performance of such carriers is affected by various factors such as, for example, the raw material used, producing method, pore structure, etc., and there are still many problems remaining unsolved in this regard.
The pore structure of the catalyst used plays a very important role in a heterogeneous reaction of hydrocarbons and proves a major factor that affects the catalyst performance.
Many studies and efforts have been made in the past toward realizing improvement of such pore structure in the catalyst, and the results of such studies have been presented in applications for catalytic conversion or refining of hydrocarbon oils. Among the typical examples of heretofore proposed methods are, for instance, a method wherein a catalyst, in which the pores of greater than 0.05 .mu. (500 A) in diameter assume 40 to 70% of the total pore volume, and in which the pores of from 0.05 to 1 .mu. (500 to 10,000 A) in diameter account for more than 30%, is used for the purpose of producing gas oils having a high diesel index by using a heavy oil as raw material; a method wherein a catalyst in which the volume of the pores greater than 80 A in radius is restricted to less than 10% of the total pore volume is used for preventing ingress of asphalt or metal-containing compounds in the residue in sulfur-bearing residue hydrodesulfurization; and a method wherein a catalyst in which the pores of less than 120 A in radius are relatively uniformly distributed is used in above-said hydrodesulfurization of sulfur-containing residual oils.
However, none of these methods discloses all the cases involving distribution of the pores of greater than 300 A in radius, and the influences derived therefrom are ignored. Also, no proposal suggestive of utilization of such methods for production of lubricating oils having a high viscosity index has been made.